With the increased demand for millimeter-wave based RF systems, there has been a corresponding interest in integrating these RF systems on silicon-based integrated circuits instead of using discrete III/V based semiconductor components. Millimeter-wave frequencies are generally defined to be between about 30 GHz and 300 GHz. Common applications for millimeter-wave base RF systems include, for example, automotive radar and high-frequency communications systems. By using silicon integration, larger volumes of these RF systems can be manufactured at a lower cost than discrete component based systems.
Testing millimeter wave based systems, however, is difficult and expensive. For example, in systems that operate at over 10 GHz, the precision test fixtures and equipment used to test these systems are expensive. These test fixtures and equipment are time consuming to operate, calibrate and maintain, and the RF probes used for testing have a limited lifetime and wear out over time. Physical deformations, such as bent contacts, can affect high-frequency matching networks, and corrosion of contacts and connectors can degrade attenuation characteristics of the test setup. Furthermore, the expertise required to maintain and operate such high-frequency test equipment is not often available in the high-volume semiconductor test environments. As such, even if large volumes of millimeter-wave RF integrated circuits can be manufactured, testing the integrated circuits can become a large bottleneck.
FIG. 1 illustrates, for example, conventional RF integrated circuit test setup 100. RFIC 102 having RF circuit 104 is packaged in package 106. RF test fixture 108 is coupled to package 106. In such a system, RF testing of RFIC 102 is performed by RF test fixture 108 at high frequencies. One way to save test time and cost is by not performing a full test of the RF signal path. In some systems, such as radar-based automotive collision warning systems, full and comprehensive testing may be needed to ensure safety and reliability of the system.